I'm presented with the problem below, where $X$ and $Y$ are unknown. $$\begin{cases}X - 100,000 = Y\\(Y/X) \cdot 100 = 25\end{cases}$$ Is there any formula to figure out the value of $X$?
Asked
Active
Viewed 370 times
0
-
Plug in $X-100,000$ instead of $Y $ in your second equation and solve for $X $.Then go back to the first equation and plug in the value of $X $ to obtain $Y $. – New_to_this Dec 08 '16 at 17:15
-
If you mean that $Y$ should be $25%$ of $X$, then write either $(Y/X)\cdot 100 = 25$ or $(Y/X) = 25%$, but not both. Remember, $25%$ means $25/100$. – MPW Dec 08 '16 at 17:22
-
@MPW thank you, I have corrected the formula. – Joe Cambareri Dec 08 '16 at 17:34
1 Answers
0
We substitute $Y$ by $X-100,000$ in the second equation
We have $$\frac{X-100,000}{X}=\frac{25}{100}$$
Multiplying X on both sides $$X-100,000=\frac{25}{100}X$$
or $$\frac{75}{100}X=100,000$$
or $$X=100,000\frac{100}{75}\approx 133,333.33 $$
Finally , $Y=X-100,000\approx 133,333.33-100,000\approx 33,333.33$
Canardini
- 4,147
-
1You don't have to guess. If $X$ satisfies those equations, then it is nonzero. – MPW Dec 08 '16 at 17:37
-
I think I understand what you're doing here, however, it is not coming out to the answer that I'm expecting. I'm expecting $X$ to be somewhere around 133,500. In that way, $Y$ is at least 25% of $X$. Does that make sense? – Joe Cambareri Dec 08 '16 at 19:18
-
It seems that the question was edited. Before it was $$\begin{cases}X - 100,000 = Y\(Y/X) \cdot 100 = 25%\end{cases}$$ – Canardini Dec 08 '16 at 19:24
-
-